Frost Dates & Planting Calendar for Rio Grande City, TX

The average first fall frost in Rio Grande City, TX is December 17, and the average last spring frost is January 31, giving a growing season of about 321 days.

Plan your garden around Rio Grande City, TX's typical frost-free growing season, using NOAA climate normals and a 42-crop planting calendar built for this location.

Last Spring Frost

January 31

Safe Mar 4 Typical Jan 31 Risky Dec 29

First Fall Frost

December 17

Safe Nov 22 Typical Dec 17 Risky Jan 20

Growing Season

321 days

Typical last frost to typical first frost.

USDA Hardiness Zone

Zone 9b

Subtropical to frost-free — heat, not cold, is the main limit on what you can grow.

Data: NOAA station RIO GRANDE CITY, TX US, 0.9 km away.

— days until the typical last spring frost

How Rio Grande City Compares

Rio Grande City's typical last spring frost (Jan 31) comes earlier than in 83% of the 258 Texas cities we track.
Its 321-day growing season is 62 days longer than the Texas median of 259 days.
Compared with Alton (52 km away), Rio Grande City's last spring frost comes 8 days later than Alton's, and its first fall frost arrives 11 days earlier.
August is the warmest month (average high 99°F) and January the coldest (average low 45°F).

Monthly Temperatures

Avg. high Avg. temp Avg. low

Planting Calendar

Vegetables
Crop	Start indoors	Direct sow	Transplant	Fall planting	Maturity	Notes
Tomato	Dec 6 – Dec 20	—	Feb 7 – Feb 14	—	60–85 days	Start indoors 6-8 weeks before last frost; transplant out 1-2 weeks after last frost once soil has warmed.
Pepper	Nov 22 – Dec 6	—	Feb 7 – Feb 21	—	60–90 days	Slow to germinate; start indoors 8-10 weeks before last frost. Transplant only once nights stay above 55F, 1-3 weeks after last frost.
Eggplant	Nov 22 – Dec 6	—	Feb 14 – Feb 21	—	65–85 days	Warm-season crop, similar timing to pepper; needs consistently warm soil (65F+) to transplant.
Cucumber	Jan 3 – Jan 10	Feb 7 – Feb 14	Feb 7 – Feb 14	—	50–65 days	Can be started indoors 3-4 weeks before transplanting, or direct-sown 1-2 weeks after last frost once soil is warm.
Zucchini	Jan 10 – Jan 17	Feb 7 – Feb 21	Feb 7 – Feb 14	—	45–55 days	Fast-growing squash; direct sow 1-3 weeks after last frost, or start indoors 2-3 weeks early for a head start.
Winter Squash	Jan 3 – Jan 10	Feb 7 – Feb 21	Feb 7 – Feb 14	—	80–110 days	Long season; direct sow after soil warms, or start indoors 3-4 weeks before last frost in short-season climates.
Pumpkin	—	Feb 7 – Feb 21	—	—	90–120 days	Direct sow 1-3 weeks after last frost; back-time from your first fall frost so the 90-120 day maturity window lands before it.
Watermelon	Jan 3 – Jan 10	—	Feb 14 – Feb 21	—	70–90 days	Needs warm soil (65F+); start indoors 3-4 weeks before last frost, transplant 2-3 weeks after last frost.
Cantaloupe	Jan 3 – Jan 10	—	Feb 14 – Feb 21	—	70–90 days	Same warm-soil requirements as watermelon; avoid disturbing roots when transplanting.
Corn	—	Jan 31 – Feb 14	—	—	60–100 days	Direct sow at last frost to 2 weeks after, once soil reaches 60F; does not transplant well. Succession sow every 2 weeks.
Green Bean	—	Jan 31 – Feb 14	—	—	50–65 days	Direct sow at last frost to 2 weeks after, once soil has warmed; frost-tender, do not rush.
Pea	—	Dec 20 – Jan 3	—	—	55–70 days	Cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked.
Lettuce	—	Jan 3 – Jan 17	—	Oct 22 – Nov 5	45–60 days	Cold-hardy; direct sow 2-4 weeks before last frost. Also transplantable from indoor starts.
Spinach	—	Dec 20 – Jan 3	—	Oct 22 – Nov 5	40–50 days	Very cold-hardy; direct sow 4-6 weeks before last frost as soon as soil can be worked.
Kale	—	Jan 3 – Jan 17	—	Oct 8 – Oct 22	50–65 days	Cold-hardy; direct sow 2-4 weeks before last frost or start indoors for earlier transplants.
Arugula	—	Jan 3 – Jan 17	—	Nov 5 – Nov 12	30–40 days	Fast-growing, cold-tolerant green; direct sow 2-4 weeks before last frost, succession sow every 2-3 weeks.
Swiss Chard	—	Jan 10 – Jan 24	—	—	50–60 days	Fairly cold-hardy; direct sow 1-3 weeks before last frost. Tolerates light frost in fall too.
Broccoli	Dec 13 – Dec 27	—	Jan 10 – Jan 17	Oct 15 – Oct 22	55–80 days	Start indoors 5-7 weeks before last frost; transplant out 2-3 weeks before last frost (hardens off to light frost).
Cauliflower	Dec 13 – Dec 27	—	Jan 17 – Jan 24	Oct 8 – Oct 15	55–85 days	Fussier than broccoli about temperature swings; start indoors 5-7 weeks before last frost, transplant 1-2 weeks before last frost.
Cabbage	Dec 13 – Dec 27	—	Jan 3 – Jan 17	Oct 8 – Oct 22	60–100 days	Cold-hardy; start indoors 5-7 weeks before last frost, transplant 2-4 weeks before last frost.
Brussels Sprouts	Dec 13 – Dec 27	—	Jan 10 – Jan 24	—	90–110 days	Long-season crop best timed to mature after a light fall frost for sweetest flavor; start indoors 5-7 weeks before last frost.
Carrot	—	Jan 3 – Jan 17	—	Sep 24 – Oct 8	60–80 days	Direct sow only (does not transplant); sow 2-4 weeks before last frost, as soon as soil can be worked.
Beet	—	Jan 3 – Jan 17	—	Oct 8 – Oct 22	50–65 days	Direct sow 2-4 weeks before last frost; tolerates light frost.
Radish	—	Dec 27 – Jan 10	—	Nov 5 – Nov 19	22–30 days	Very fast and cold-hardy; direct sow 3-5 weeks before last frost, as soon as soil can be worked.
Turnip	—	Jan 3 – Jan 17	—	Oct 8 – Oct 22	40–60 days	Cold-hardy; direct sow 2-4 weeks before last frost.
Onion	Nov 22 – Dec 6	—	Jan 3 – Jan 17	—	90–120 days	Start seeds indoors 8-10 weeks before last frost (or use sets/transplants); set out 2-4 weeks before last frost, very cold-tolerant as seedlings.
Garlic	—	—	—	Nov 19 – Dec 3	240–270 days	Fall-planted crop only; not planted in spring in most climates.
Potato	—	Jan 3 – Jan 17	—	—	70–120 days	Plant seed potatoes 2-4 weeks before last frost, as soon as soil can be worked and is above 45F; light frost on emerging foliage is usually tolerated.
Sweet Potato	—	—	Feb 14 – Feb 28	—	90–120 days	Set out slips 2-4 weeks after last frost once soil is thoroughly warm (65F+); very frost/cold sensitive.
Asparagus	—	—	Jan 3 – Jan 17	—	730–1095 days	Perennial; plant crowns 2-4 weeks before last frost as soon as soil can be worked. Takes 2-3 years to full production.

Herbs
Crop	Start indoors	Direct sow	Transplant	Fall planting	Maturity	Notes
Basil	Dec 20 – Dec 27	—	Feb 7 – Feb 14	—	50–70 days	Very frost/cold sensitive; start indoors 5-6 weeks before last frost, transplant only after all danger of frost (1-2 weeks after) and nights stay warm.
Cilantro	—	Jan 10 – Jan 24	—	Oct 22 – Nov 5	45–70 days	Cool-season, bolts in heat; direct sow 1-3 weeks before last frost, succession sow through spring.
Parsley	Dec 6 – Dec 20	—	Jan 17 – Jan 24	—	70–90 days	Slow to germinate; start indoors 6-8 weeks before last frost, transplant 1-2 weeks before last frost (biennial, cold-tolerant).
Dill	—	Jan 10 – Jan 24	—	—	40–60 days	Taprooted, does not transplant well; direct sow 1-3 weeks before last frost, succession sow through summer.
Oregano	Dec 6 – Dec 20	—	Jan 31 – Feb 7	—	80–90 days	Perennial herb; start indoors 6-8 weeks before last frost, transplant around/just after last frost date.
Thyme	Dec 6 – Dec 20	—	Jan 31 – Feb 7	—	85–95 days	Perennial herb, slow from seed; start indoors 6-8 weeks before last frost, transplant around/after last frost.

Flowers
Crop	Start indoors	Direct sow	Transplant	Fall planting	Maturity	Notes
Sunflower	—	Feb 7 – Feb 21	—	—	70–100 days	Direct sow 1-3 weeks after last frost once soil has warmed; taprooted, resents transplanting.
Zinnia	Jan 3 – Jan 10	Feb 7 – Feb 21	Feb 7 – Feb 14	—	60–70 days	Frost-tender; direct sow 1-3 weeks after last frost, or start indoors 3-4 weeks early for earlier blooms.
Marigold	Dec 20 – Jan 3	—	Feb 7 – Feb 14	—	45–60 days	Frost-tender; start indoors 4-6 weeks before last frost, transplant after all frost danger has passed.
Cosmos	Jan 3 – Jan 10	Feb 7 – Feb 21	Feb 7 – Feb 14	—	60–90 days	Easy from direct seed 1-3 weeks after last frost; can also start indoors 3-4 weeks early.
Nasturtium	—	Feb 7 – Feb 21	—	—	50–65 days	Frost-tender, resents root disturbance; direct sow 1-3 weeks after last frost once soil has warmed.
Dahlia	—	—	Feb 7 – Feb 21	—	90–120 days	Plant tubers 1-3 weeks after last frost once soil is warm (60F+); very frost-sensitive.

Date ranges are estimates based on university extension guidelines and this city's NOAA frost normals — not a guarantee. Scroll to see all columns on narrow screens.

Frequently Asked Questions

When is the last frost in Rio Grande City, TX?

Based on 1991–2020 NOAA climate normals for the RIO GRANDE CITY, TX US station, the last spring frost in Rio Grande City typically falls around January 31. A cautious gardener might wait until March 4 (only a 10% chance of a later frost), while December 29 marks an earlier, higher-risk planting date.

When is the first frost in Rio Grande City, TX in fall?

The first fall frost in Rio Grande City typically arrives around December 17. To stay safe, assume frost could start as early as November 22; in milder years it can hold off until January 20.

How long is the growing season in Rio Grande City, TX?

Rio Grande City's average frost-free growing season is about 321 days, running from the typical last spring frost (January 31) to the typical first fall frost (December 17).

What USDA hardiness zone is Rio Grande City, TX in?

Rio Grande City, TX is in USDA plant hardiness zone 9b, per the USDA's 2023 Plant Hardiness Zone Map. Subtropical to frost-free — heat, not cold, is the main limit on what you can grow.